Hollow panels



J. H. B. HERTS HOLLOW PANELS July 7, 1959 Original Filed oc t. 14 1954 2 Sheets-Sheet 1 INVENTOR. 3% HE'M 25: 3 Einzza J. H. B, HERTS HOLLOW PANELS July 7, i959 2 Sheets-Sheet 2 Original Filed Oct. 14, 1954 INVENTOR. 'H- zt' United States Patent HOLLOW PANELS John H. B. Herts; Great'Neck, N;Y., assignor, by'mesne assignments, to Intercoastal Door Corporation,- Long Island City, N.Y., acoi'porationof New York Original application October 14, 1954;Serial N 0. 462,352, now Patent No.. 2,719,809,. dated. October 4,. 1955. Divided and this application August 15, 1955, Serial Z Claims; (Cl. 20:--91) 'Ihi's inve ntion-relates to-hollow panels and" is directed particularly to a method of manufacturing hollow' panel structural units for use as flush or panel doors, table tops, and" the hke.

Hollow panels consisting in general of a rectangular frame; usually of wood, to the front and back of which sheets or so-called skins of facing material' such as-plywood or plyboard are glued, are in general'user In order to give strength to such panels, various web or grid-like constructions of wood lathingand corrugated cardboard or paper are commonly used, these-being glued between the facing sheets; In the interest of develop ing' a less expensive hollow panel, however, attempts havebeen made to-utilize a cellular paper strengthening construction glued within the panel and" between the facings. Such paper cell panels however, because of difficulties in gluing and for other reasons that will become apparent from the following description; have'not heretofore been manufactured in commercial quantities.

invention accordingly comprises a simple and effective-process for the quantity production of panel structure of the character described, utilizing an internal cellular paper construction for strengthening.

In brief, as a principal step in the process according to my invention, the panel framework is fitted with a cellular paper construction the thickness of which is greater than the frame thickness, and is then run flatwi'sethrough steel rollers to bendover the top and bottom edgesofthe cellular paper construction so that they lie flush with the upper and lower (or front and back) planes ofthe frame.

Among other advantages of the process according to this invention, as will be apparent from the following description, such deformation of the cellular paperedges provides a' greatly increased surface area for the application' of glue and consequently insures effective and uni:- for-m' bonding; between the cellular paper strengthening insert and the finally' applied facing sheets.

It" is accordingly the principal object of my invention to provide an improved method for quantity production of panel structures having internal strengthening means of cellular paper construction.

It is another object of this invention to provide a process for the mass production of, panel units of the character described, wherein glue is applied directly to the edges of the paper construction and thereby only to the. surface areas actually to be glued, rather than to the whole inner surface of the facing sheets, whereby economy is further enhanced.

Another object of this invention is to provide a process for the mass production of panel units of the character described, wherein each panel-unit is constructed with planar parallel surfaces to within close tolerances, so that a plurality of panels can be stacked and subjfecte'd tocompression fordrying without danger offaulty internal gluingor twisting due to the accumulation of non-uniformities of thickness or non-parallelism in individual panels.

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A further object'of this invention is toprovide a new and improved method of making accurately planarpanel units that are comparatively inexpensive because of the use'of paper for internal strengthening, and yet which are comparatively strong.

Still another object is to provide a panel construction ofthe character described, containing a partial vacuum whereby its sound and heat insulating properties are enhanced;

These and other objects and features'of this invention willbe apparent from the following specification and from the attached drawings illustrating by way of example the process according to the invention applied to the manufacture of a paneldo'or.

In the drawings:

Fig; 1 illustrates a door according to the invention, portions being broken away to show internal construction;

Fig. 2 is an enlarged view taken along the line 2-2' of Fig; 1,. a central section being broken away;

Fig; 3 is anenlarged" cross-sectionalvi'ew taken. along the line 33 of Fig, l, a central section and end sections'being broken away;

Fig. 4' is a perspective view of a portion of the cellular paper construction used as the strengthing means within the'door' fabricated in accordance with the method comprising this invention;

Fig. 5 is an elevational viewillustrating how the end members of the panel f'rameare. glued to the paper structure while in unextended condition;

Fig. 6 is a vertical cross-sectional view taken along the lined-6 of Fig. 5

Fig. 7 illustrates how the panel frame together with its inserted paper strengthening structure is passedthrough steel rollers in accordance with. the invention to turn over and. size the edges to frame thickness;

Fig. 8 isan enlarged view in cross-section showingin detail the deformation of the paper edges during passage through the steel rollers; and

Fig; 9 illustrates how glue can be applied to the frame. and. deformed paper edges just prior toassembly of. thefacing sheets.

Referring now to the drawings, Fig. 1; illustrates a. completed door having upper and lower ends or rails 10 and 12, side. frame members or stiles. 14 and 16, and. front and back facing sheets. 18 andv 20,. respectively According to the invention, the interior strengthening structure for the door comprises a paper cellular com.

struction indicated. generally by the number 22.. As

well known, sucha paper structure consists of. aplurality. of side by side paper strips so. glued together so thatwhen the structure, called. a slice in the trade, is sufliciently extended, hexagonal cells are developed, as. best seen in Fig. 4. As illustrated in Figs. 5 and 6; the. panel is fabricated byfirst gluing the upper and lower railsv 10. and I2 to the upper and lower sides of the paper. (1on1 stnuction or slice 22 before its extension. The glue is. indicated by numeral 24 Because the paper construetion 22 Will contract in width after its extension, it. is-

made wider to begin with than the rails 10 and 12,. as:

shown in Fig. 5. In accordance with the process comprising this invention, moreover, the thickness of thepaper construction 22 issomewhat greater than thethick,

ness of the rails 10' and 12' to whicli it is glued, as illus-- trated in Fig. 6.

After the glued assembly ofthe. rails 10' and 12 andthe paper structure or slice 22 has. thoroughly dried, saidrails are separated to extend the paper structure so as topoints, two or three cells of every fourth or fifth row of cells are vertically slit as indicated by the numerals 23. In this way maximum economy of paper use is obtained and the weight of the finished door is at the same time further reduced. 7

The rails 10 and 12 are then secured in butt joint fashion between the upper and lower ends of the stiles, as best seen in Fig. 1. The framework thus formed is held together in any conventional manner such as by the use of furniture nails 26. During the extension of the paper slice 22 its width will have diminished to suchan extent that it substantially just fills in the space between the side stiles 14 and 16.

4 through use of the improved process described herein, to provide an exceptionally strong door of low conductivity. The process, moreover, is extremely economical both in its use of materials and its requirements as to time and labor.

Interior paper constructions 22 made of ordinary kraft paper as thin as .009 inch have been found to be entirely satisfactory for use in the process according to the invention. Inserts made of paper of such thinness would merely crumple if an attempt were made to apply the facing sheets to the framework under pressure without the intermediate rolling steps described herein, whereby the edges are progressively folded over at right angles.

The next step in the panel construction process is the 7 pressure roller treatment of the completed framework together with its interior cellular paper construction 22, as illustrated in Figs. 7 and 8. In order to prevent the paper construction 22 from hanging heavily from between the end rails 10 and 12 during subsequent handling, however, it is preferably first to lightly tack the sides of said paper construction against the inside surfaces of the stiles 14 and 16.

Fig. 7 illustrates a pair of steel rollers 26 spaced from each other at the thickness of the rails 10, 12 and the stiles 14, 16, and driven to rotate as indicated by the arrows. The framework is passed between the rollers 26 as illustrated, whereupon the oversize upper and lower This is a divisional application of my co-pending application Serial No. 462,352, filed October 14, 1954 and assigned to the assignee hereof, which application has issued as Patent No. 2,719,809.

While there has been shown and described herein a particular way in which the method according to the invention can be carried out, it will be understood that various changes and modifications can be made without departing from the invention. The appended claims 7 therefore are meant to cover all such changes and modifiedges of the cellular paper construction 22 are bent over v bend over by substantially the same amount during the rolling process for the reason that the top and bottom edges of said paper construction are more readily subject to deformation than its central portion. In other words, the central portion of the thickness of the paper construction is stronger than the outermost top and bottom portions as illustrated in Figs. 7 and 8.

As best illustrated in Fig. 8, the rolling operation bends over the top and bottom portions of the cellular paper construction in a more or less haphazard fashion to provide end surfaces 28 of greatly increased area and substantially flush with the major planes of the frame. 'I hese surfaces 28 are capable of holding a suflicient quantity of glue for subsequent gluing to the facing sheets, whereas, by comparison, clean cut edges of the paper itself would be incapable of holding enough glue to insure satisfactory gluing even if it could be placed flush against a facing sheet.

The pressure-rolled framework is next run through a pair of resilient gluing rollers 30, as illustrated in Fig. 9, whereupon upper and lower layers of glue 32, 34, respectively, are applied to the framework construction.

One of the facing sheets, the lower facing sheet 18 for example, is next placed against the lower glued side of the framework construction and the assembled structure is then subjected to heat furnished by a heat radiating appliance or a hot air blower. The remaining facing sheet 20 is then applied while the structure and the air enclosed is hot. The glue kept tacky by the heating process, is then allowed to dry. Upon cooling, a partial vacuum develops the door to improve its insulating properties. The drying is preferably done under pressure. Since each panel will have planar surfaces with little deviation from parallelism because of the rolling operation, many assembled panels can be piled for drying together in a single press without danger of warping or other detrimental effects as might be caused by accumulative dimensional deviation in individual panels. Practically one hundred percent effective bonding between the edges of the paper construction 22 and the inner surfaces of the facing sheets 18, 20 also results cations as fall within the true scope and spirit of the invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A structural panel, comprising a rectangular frame of predetermined thickness, a cellular core insert mounted within said frame with opposite ends of said core glued to inner surfaces of the opposite ends of said frame, said core having a plurality of slits provided therein adjacent said ends thereof and being formed of strips of flexible sheet material secured together to define a plurality of cells, each cell having a pair of opposed walls of double strip thickness interconnected by walls of single strip thickness, said core walls terminating in opposite. core faces defined by integral flanged gluing porness of said frame, said peripheral walls being bent at their outer edges transversely to said thickness direction of the frame to provide the core with integral flangedv gluing portions at the opposite sides thereof, said flanged portions being substantially flush with the adjacent surfaces, respectively, of said frame, and a facing member glued to the flanged gluing portions in surface-to-surface relation therewith at each side of said frame, said core being formed-of strips of flexible sheet material secured together to define the cells thereof, and said core being slit adjacent the ends thereof to minimize bunching of saidstrips.

References-Cited in the file of this patent UNITED STATES PATENTS 2,3s5,352 Davis Sept. 25, 1945 2,511,620 Clements June 13, 1950 2,609,315 Engel et a1. Sept. 2, 1952 12,662,043 Clements Dec. 8, 1953 FOREIGN PATENTS 1 323,960 Italy Jan. 14, 1935 558,166 Great Britain 1943 1,011,146 France Apr. 2, 1952 

